Apparatus for drying sheet material



Nov. 13, 1951 w. F. RODEN APPARATUS FOR DRYING SHEET MATERIAL 2SHEETS--SHEET 1 Filed April 16, 1949 INVENTOR. WILLIAM FRoDEN Nov 13,1951 w. E. RODEN APPARATUS FOR DRYING SHEET MATERIAL Filed April 16,1949" 2 Sl-lEETS-SI-EJET 2 IN V ENTOR.

' \AZILLIAM F RoDEN n =4 3 Attorney Patented Nov. 13, 1951 UNITED STATESPATENT OFFICE William nnoah, Carl Place, N. Y.

Application April 16, 1949, Serial No. 87,901

This invention relates to an improved apparatus and method for dryingthe surface of moving continuous sheet or strip material on which a wetfilm has been deposited, such as H the printing ink applied by aprinting press to" the surface of paper, cellophane or cloth webs.Various methods and devices have been used for drying printing ink, onebeing the conditioning or dehumidifying of the air in the entire roomwhere the printing press is operated. Another method is to run theprinted web or strip through a closed chamber containing air dried byapplication of heat, or by other means, completely surrounding the webin contact with both which materially limits the output that the printing press is capable of delivering, since each application of ink mustbe thoroughly dried before successive applications can be made or theweb rolled or folded in the'final operation. In addition, it is oftendiflicult to obtain an even and uniform distribution of the treated airover the printed surface of the web, resulting in uneven andincompletedrying. a

It is an object of the present invention to provide an improvedapparatus and method for drying the wetted surface of moving continuoussheet material, such as the printed web of printing presses, whichrequires the treatment ordrying of only a minimum amount of air and inwhich the maximum amount ofthe treated air is effectively used in thedrying process.

Another object of the invention is the provision of an apparatusandmethod as above described in which a relatively thin layer'ofdehydrated air is passed over the surface to be dried at high velocity,resulting in the rapid and even drying of the surface.

Still another object of the invention is to provide an apparatus of thecharacter described which occupies a minimum amount of space and whichmay be installed for use with existing or alteration of the machine.

3 Claims. (Cl. 34-159) A further object of the invention is to providean apparatus as above described in which a maximum amount of the airthat is treated is recovered and reconditioned for continuous reuse.

These and other objects of the invention will be apparent to thoseskilled in the art from a study of the following description andaccompanying drawings, in which:

Figure 1 is a side elevational view showing the apparatus installed foruse with a printing press or similar machine where the drying of a wet'film applied to the surface of moving continuous sheet material-isrequired.

Figure '2 is a fragmentary perspective view of the apparatus taken froma point above it and looking towards the top portion thereof.

Figure 3 is a sectional view taken on line 3-3 of Figure 2.

Figure 4 is a sectional view taken on line 44 of Figure 2.

Figure 5 is a fragmentary perspective view similar to Figure 2, buttaken from a point below the apparatus looking towards the bottomportion thereof.

Referring now more in detail to the drawings, the apparatus is shown inFigure 1 as installed for use with a printing press, diagrammaticallyrepresented at A, having rollers 6 over which travels, in the directionindicated by the arrows, a printed web 8 or similar continuous sheetmaterial to be dried. Figure 1 shows a multiple application of theapparatus installed for successively drying four separate printing inkor color applications, but this is merely for purposes of illustrationsince the apparatus may be adapted for use in drying any desired numberof separate printing or color applications.

The apparatus'comprises an enclosed air drying chamber [0 suitablymounted on the press A and containing a bed ll! of dehydrating agent,

to and of substantially the same width as the printed web surface to bedried. The delivery cone is formed with an elongated slot or orifice 22extending lengthwise of the cone and opening into an airinlet duct 24"of relatively shallow rectangular cross section. The inlet duct?! v ofthe air.

leads into and merges with the central portion of the casing 20, the topwall of which is formed at this point in the shape of a semi-Venturitube section 26. The bottom wall of casing 20 directly beneath theVenturi section 26 is formed with an opening 28 arranged in overlyingspaced relation to the surface of the web 8, as more clearly shown inFigures 2 and 4. The semi- Venturi section 26 extends beyond the opening28 and leads into an air recovery cone 30, generally similar in shape tothe delivery cone 18, but much larger and tapering in the oppositedirection. The outlet or large end of the recovery cone 30 is connectedwith a. return. con-- duit 32 leading back into the drying chamber In atthe upper part thereof above the bed $2 of the dehydrating agent, a fanindicated at 3.4 driven by motor 35 being provided in the conduit forforcibly drawing the air back intothe chamber and through, the bed ofdehydrating agent for redrying and reuse.

The apparatus is closed. to the atmosphere except at the opening 28'through. which a quantity of air sumcient for operation of. theapparatus will enter. In operation, the two motor driven fans I 4 and 34are started, the fan [4 being of sufficient power. to force air from thedrying chamber lfl' after being drawn through bed 12, into the deliveryconduit It, as indicated by the arrows in Figure 5, at a slightlypositive pressure. The dry air reaching the entrance end of the deliverycone 18 will, therefore, be slightly compressed and, of course, will berelieved through the orifice 22 into the air inlet duct- 24, asindicated. by the arrows in Figure 4. Due to the shape of cone I8,gradually reduced in capacity toward its tapering end, the air pressurewill remain uniform throughout the length of the cone, resulting in aneven flow of air at all points along the orifice 22 into air inlet duct24. The relative capacities of the cone- [8 and inlet duct 24 are suchthat the latter will hold a volume of air at atmospheric pressuresubstantially equal to the volume of air held by the cone at a slightlypositive pressure. The air will thus be received and uniformlydistributed in the inlet duct 24 at atmospheric pressure and in the formof a flat layer due to the shape of the duct. The layer of dried airthen enters the Venturi section 26 flowing in a direction counter to thedirection of travel of Web 8 as indicated by the arrows in Figure 4,passing over and contacting the surface of the web exposed to it throughthe opening 28. Due to the wellknown characteristic of the Venturi, thevelocity of the air will be greatly increased at this point and also thethickness of the layer of flowing air will be reduced. The same volumeof air will flow over the web surface 8- as is contained in inlet duct24 but in a shorter time'due to its higher velocity, resulting in fasterdrying than otherwise would be the case. Moreover, a maximum percentageof the dry air will actually contact the web surface a in the dryingprocess due to the reduced thickness of the layer of air, resulting in amore effective and economical use In addition, the uniform distributionof the air in contact with the web surface results in even drying.

After passing over and absorbing moisture from the web surface 8, thehumid air now flows through the flared or after-portion of the semi-Venturi section into the recovery cone 30 where it expands due to therelatively larger space provided by the cone that the air then has tooccupy. This expansion of the air into the relative large volume of therecovery cone 30 and from there into the large return conduit 32 lowersits pressure to a degree producing suction in this part of theapparatus, further increasing the speed of the flowing air in itspassage over the web surface 8. Since the layer of air is flowing athigh velocity at atmospheric pressure and in laminar flow and due to theshape of the: after'portion of the Venturi section 26, the air isinducedto enter recovery cone 30. In other words, due to another well-knowncharacteristic of the venturi, substantially all of the flowing air willtend to follow or be guided by the flared wall of the Venturi sectioninto the recovery-cone. Thus, the loss of dry air escaping. to theatmosphere and the entry of untreated atmospheric air through opening 28into the apparatus are reduced to a minimum. In addition, the drawingpower of fan 34 is such as to be su-fiicient of itself to producesuction in return conduit. 32, thus further assuring, recovery ofsubstantially all of the air for return to and redrying inthe chamber HIby passage through the bed [2 of dehydrating agent for reuse.

Supplying the air to the delivery cone under pressure perm-its the. useof the comparatively small conduit i6. With this; arrangement the air isreceived in inletduct 24f at substantially atmospheric pressure and inthe form. of a flat layer prior to passage through Venturi section 26andover the web surface 8, avoiding the necessity of providing largecumbersome air ducts for this purpose. Another important advantage of.the apparatus is the faster drying process resulting from an increase inthe velocity of the dry air flowing over the wet surface and in adirection counter to the direction of travel of the web surface. Adrying apparatus has been provided in which only a minimum quantity ofair is required to be conditioned and in which a maximum amount of theconditioned air is effectively used in the drying process, resulting ineconomical operation. Further economy of operation is obtained by theredrying: and reuse of the air, the only moisture absorbed by the bed I2of dehydrating agent from the flowing air being confined substantiallyto only that absorbed by the air from the web surface 8. In otherwords,,since only a minimum amount of outside: or atmospheric air entersthe apparatus during operation, substantially the same air iscontinuously redried and reused. Thus a smaller amount of dehydratingagent is. required and this can be used for a longer period of timebefore it has to be regenerated.

The invention may be modified in various respects as will. occur tothose skilled in the art and the exclusive use of all modifications ascome within the scope of the appended claims is contemplated.

What is claimed is:

1. In an apparatus for progressively drying a wetted surface ofcontinuous sheet material, in combination with means for moving saidmaterial, a casing having a'bottom wall formed with an opening inoverlying spaced relation to said surface, means for continuouslydelivering a layer of flowing dehydrated air to one side of said casingin contact with said surface through the casing opening, said casinghaving a top wall formed as a semi-Venturi tube section above openingwhereby to simultaneously increase the velocity and reduce the thicknessof said flowing layer of dehydrated air'contacting said surface as thesheet material is moved along its path beneath the opening, andcone-shaped outlet means at the other side of the casing acting torecover said air therefrom by suction after it has contacted saidsurface of the sheet material.

2. An apparatus for progressively drying a wetted surface of continuousmoving sheet material comprising a casing of substantially the samewidth as said material having a bottom opening spaced from and overlyingsaid surface and including an air delivery cone and an air recoverycone, an air dehydrating chamber, means for continuously supplyingdehydrated air from said chamber to said delivery cone under pressure,said air being received by said casing at reduced pressure in the formof a layer, said casing'being formed with means for simultaneouslyincreasing the velocity of and thinning said layer of flowing air as itcontacts said surface through the casing opening, said recovery conebeing of greater air capacity than said delivery cone and extending inthe opposite direction whereby to recover said air by suction afterflowing over said surface, and means for returning said air from saidrecovery cone back to said chamber for redrying and reuse.

3. In an apparatus for progressively drying a wetted surface ofcontinuous moving sheet material, a casing of substantially the samewidth as said material provided in its central portion with a bottomopening spaced from and overlying said surface, said casing being formedas a semi-Ven- 6, turi section over said opening and including an airinlet duct, an air delivery cone opening into said duct, an air recoverycone leading from said semi-Venturi section, an air dehydrating chamber,means for continuously supplying'dry air from said chamber to saiddelivery cone under pressure, said inlet duct being adapted to receiveair from said delivery cone at reduced pressure in the form of a layer,said semi-Venturi section acting to simultaneously increase the velocityof and thin said layer of flowing air as it passes over in contact withsaid surface through, thecasing opening, said recovery cone acting toproduce suction whereby said air is recovered after passing over saidsurface, and means for returning said air from said recovery cone backto said chamber for redrying and reuse.

WILLIAM F. RODEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,349,590 Tensfeldt Aug. 17, 19201,847,915 Bailey Mar. 1, 1932 2,205,391 Brunkow June 25, 1940 FOREIGNPATENTS Number Country Date 427,028 Great Britain Apr. 15, 1935

